Lamp switching mechanism



Jan. 25, 1938. J PQTE 2,106,413

LAMP SWITCHING MECHANI SM Filed June 11, 1928 INVENTOR.

A TTORNE Y.

Patented Jan. 25, 1938 UNITED sTArs LAMB SWITCHING MECHANISM Alfred J. Pot, Chelsea, Mass., assignor, by mcsne assignments,

Delaware Baythcon Manufacturing Company, Newton. Mm, a corporation of Application-June 11. 1928, serial No. 284,498 13 Claims. (01. 176-124)- My invention relates to lamp switching mechanism and has particular reference to the switching on and oil of electric glow-lamps. The electric glow-lamp consisting of spaced electrodes in an atmosphere of a rare or other kind of gas has been used quite extensively for illuminating and advertising purposes. For the latter purpose it lends itself readily to the formation of letters or figures in. which a continuous band of illumination or glow is desired.

In the case of signs having incandescent bulbs tomary to flash or obtain various combinations of lights or groups of lights to either successively delineate a letter, word, or figure, or to illuminate continuously varying portions of a sign. In the case of glow-lamps this has been practically impossible. rule, require an extremely high potential to initiate the discharge, the potential being as high as twenty thousand volts. Thereafter, it has been customary to have resistances or automatic switching arrangements whereby a lower running potential was impressed on the glow-lamp. Even this running potential, however, is as a rule very high, amounting to' thousands of volts. To switch glow-lamps on and off for various intervals with voltages as high as are in use, presents very serious switching problems and may require expensive and complicated apparatus.

By my invention it is possible to flash the luminous portions of the glow-lamp on and oil as often and as quickly as may be found desirable. I accomplish this with simple apparatus, and in such a way that no contacts are. made or broken in the high potential circuit.

In the patents to Charles G. Smith, Nos. 1,617,172, 1,617,173 and others issued to him on February 8, 1927, a tube is disclosed wherein two spaced electrodes are surrounded by a rarefied atmosphere, preferably of one of the rare gases. The spacing between the electrodes and the pressure of the gas are so co-related thatthe gap between the electrodes is insulating under normal conditions. I

This depends upon the so-called short path principle, which is fully explained in the patents referred to above, as well as other patents of Smith. Briefly this principle is that if two surfaces are so close together that their distance is of the order of the mean free path of the surrounding gas, any free electronscoming from the cathode will not be able to travel a great enough distance to cause any substantial amount of ionization by impact. Hence, conduction beticles, conduction The glow-lamps used for signs as a tween the electrodes will not occur. If, however, the path of the electrons is so lengthened between the opposing electrodes that the electrons have several ionizing collisions with the gas parbetween the electrodes will be initiated.

There are various ways of lengthening the paths of the electrons without changing the physi'cal spacing of the electrodes as disclosed in the above entitled patents. One way in particular is by impressing a magnetic fleld.in such a way as to cause the electrons to be deflected from directly following the potential gradient and thus take a longer path. I apply this principle to the flashing of glow-lamps or the like in a. sign. By making each glo -.lamp unit with two electrodes at one end located within an insulatingly short distance from each other and surrounding that end with a solenoid, the other end of the lamp having the usual electrode, it is possible to switch the current from the two opposite electrodes to the two electrodes at one end by arranging a suitable commutating or switching mechanism. Thus it is possible to cause any number of glow-lamps to be switched on and off in any desired sequence.

The single figure of the drawing is a diagrammatic embodiment of my invention.

The drawing shows the two letters U and S, as an exampleof a sign which it is desired to flash. As is well known, the intermediate or visible portions of the glow-lamp comprising the letters U and S here do not include the electrodes. As shown here, the electrode portions of the letter U have been placed in the same plane as the intermediate U portion of the tube, but ordinarily this is not so. The ordinary practice is to have these end portions-sunk in behind the letter portion itself and usually behind the metallic covers of the sign. Furthermore the electrode or end portions of the glow-lamps usually become blackened with the sputtered metal from. the electrodes and in a short time become opaque. Hence, it is immaterial where the electrode-por tions of the glow-lamp are placed.

The glow-lamp U has electrode portions I g and 2. These portions comprise the usual glass Dress with the lead-in wires sealed therein and supporting the electrode. Portion I comprises a cylindrical electrode 3 with which and in concentric relation thereto is another open ended cylindrical electrode 4. The entire lamp is exhausted and filled with some gas as usual. Electrodes 3 and 4 are connected by means of conductors 5 and 6 to the opposite sides of transformer I, which supplies the necessary potential and current to operate each letter of the sign. At the other end of the letter is electrode 8 similar to electrode 4 and connected to electrode 4 by means of a conductor 8, Between the secondary of transformer 1 and electrodes 4 and 3 is a resistance It which is used to dissipate a portion of the voltage after the discharge through the tube has been initiated. Around portion is placed solenoid or coil II which is connected by conductors l2 and I3 to a battery l4 and switch 18.

The letter 8" is similar in all respects to the letter U with regard to the structure and comprises the' two electrode portion 2| and the one electrode portion 22. Portion 2| has concentric electrodes similar to the electrodes of the letter U". Conductor 28 connects the inner electrode through a resistance 3|! to transformer I. Electrode portion 22 is connected to conductor 28 by conductor 28. Conductor 25 connects the outer electrode of portion 2| of the letter "S to" the other end of the secondary of transformer 'l as shown. Portion 2| of the letter "S has amagnet coil 3| around it and connected to conductor l2 and switch l5 by means of conductors 35 and 38 respectively.

Electrodes 3 and 4 in portion areboth cylindrical and so related to each other that the distance between the surfaces is normally insulating under the conditions of gas pressure and kind of gas used in the letter "13. When transformer I is energized, the open circuit potential of the secondary will be impressed across electrodes 3 and 4 and electrodes 3 and 8. Due to the insulating nature of the gap between electrodes 3 and 4, a discharge will be initiated between electrodes 3 and 8 only. As soon as the discharge is initiated and current flows, the drop across resistance Ill will reduce the potential across electrodes 3 and 8 to the desired running potential. By switching battery |4 into the coil circuit of this tube, the gap between electrodes 3 and 4 will be rendered conducting by the magnetic field because of the longer electronic paths. The result will be that the entire discharge will be transferred from between electrodes 3 and 8 to electrodes 3 and 4, and the intermediate or U portion of the tube will therefore no longer be luminescent. The same applies to the letter S. By suitably actuating switch l5, it is possible to thus flash the letter U and S successively. It is of course, very easy to arrange the coil circuits so that the letters are flashed on and of! simultaneously.

Although each glow-lamp as shownhere is rendered alternately or successively dark and luminescent, the discharge itself never dies out.

However, for practical purposes and as far as the parts of the lamp which are exposed to the public are concerned, the tube may be said to be switched on and off. When the letter or intermediate portion of the tube is dark, the discharge between the two electrodes at one end is occurring. Since this end, as well as the other end containing the single electrode, as stated above, is usually hidden,

the short path discharge is invisible. In order to render the'discharge at portion I thoroughly invisible, electrode 3 may have its end closed by The cylindrical portion 3 may be solid metal or may be of gauze. Since the glass end of portion I usually becomes blackened from the sputtered metal, the discharge will not be visible if gauze is used. However, if the cylindrical portion of electrode 3 is made of .solid metal, it is desirable that there be one or more holes so that free access. to electrode 4 may be had by the gas particles in the tube.

While I have shown my invention applied to two letters, it is obvious that it can be applied to any number of letters or in fact to any number of glow-lamps arranged in any configuration whatever. Instead of letters, the tubing may be bent into shapes delineating figures or designs and any desired portion or portions thereof may be switched on and off in any and every possible way.

I claim:

1. A glow-lamp comprising a transparent envelope, an electrode at each end, a gas filling therein, said electrodes adapted to permit a discharge through the gas and render the intermediate portions of the tube luminescent, an additional electrode spaced a normally insulatingly short distance away from one of the electrodes and means for connecting said additional electrode directly through a low impedance path to the other electrode.

2. A glow-lamp comprising a transparent envelope, an electrode at each end thereof, a gas filling therein, said electrodes adapted to permit a. discharge through said gas filling and renderthe intermediate portions of the tube luminescent, an additional electrode disposed a normally insulatingly short distance from one electrode,

means for connecting said additional electrode to the other electrode, and means for destroying the normally insulating properties of the gap between said closely spaced electrodes, whereby an additional path is provided for the original current between the two end electrodes.

3. A glow-lamp comprising a transparent envelope, an electrode at each end thereof, a gas filling therein, said electrodes being adapted to permit a discharge through the gas and render the intermediate portions of the envelope luminescent, at least one of said electrodes being a hollow cylinder, an additional electrode in coaxial relationship with said cylindrical electrode and spaced a normally insulatingly short distance from said cylindrical electrode, and meansfor connecting said additional electrode directly through a low impedance path to the other electrode so as tobe at substantially the same potential as the other electrode.

4. A glow-lamp comprising a transparent envelope, a hollow cylindrical electrode at each end thereof, a gas filling therein, said electrodes being adapted to support a discharge through the gas and render the intermediate portions of the envelope luminescent, and an additional hollow cylindrical electrode having a common axis with the other of said first mentioned electrodes so as to .be at substantially the same potential as the other electrode.

5. A gaseous discharge device comprising an envelope, a pair 'of'electrodes within said envelope, an ionizable atmosphere within said envelope, said electrodes adapted to permit an ionizing discharge between them through said ionizable atmosphere, an additional electrode disposed a normally insulatingly short distance from one of said electrodes, means for connecting said additional electrode to the other of said electrodes, and means for destroying the normally insulatbetween said closelynormally insulatingly short distance from one of said electrodes, and means for creating a magnetic field in the space between said closely spaced electrodes to increase the length of the electron paths in said space and break down the normally insulating properties of said space.

7. A gaseous discharge device comprising an envelope, a pair of electrodes within said envelope, an ionizable atmosphere within said envelope, said electrodes adapted to permit an ionizing discharge between them through said ionizable atmosphere, an additional electrode disposed from one of said main electrodes a distance of the order of the molecular mean free path of said atmosphere, and means for connecting said additional electrode directly through a low impedance path to the other of said electrodes.

8. A gaseous discharge device comprising an envelope, a pair of electrodes within said envelope, an ionizable atmosphere within said envelope, said electrodes adapted to permit an ionizing discharge between them through said ionizable atmosphere, an additional electrode disposed closer to one of said main electrodes than the distance between said main electrodes, a circuit connecting a source of potential between said main electrodes, an auxiliary circuit connecting a source of potential between the additional electrode and the main electrode adjacent to it, an impedance common to both of said circuits, and means for controlling the current flowing between said closely spaced electrodes to control the current flowing between said main electrodes.

9. A gaseous discharge device comprising an envelope, a pair of electrodes within said envelope, an ionizable atmosphere within said envelope, said electrodes adapted to permit an ionizing discharge between them through said ionizable atmosphere, an additional electrode disposed closer to one of said main electrodes than the distance between said main electrodes, a circuit connecting a source of potential between said main electrodes, an auxiliary circuit connecting a, source of potential between the additional electrode and the main electrode adjacent to it, means for controlling the current flowing between said closely-spaced electrodes, and means responsive to the said current for controlling the potential applied between said'main electrodes.

10. A gaseous discharge device comprising an envelope, a pair of electrodes within said envelope, an ionizable atmosphere within said en- 'velope, said device being adapted to permit an ionizing discharge between said electrodes through said ionizable atmosphere, an additional electrode disposed closer to one of said main electrodes than the other of said main electrodes, means for connecting said additional electrode to the other of said main electrodes, and means for controlling the current flowing between said closely-spaced electrodes to control the current flowing between said main electrodes.

11. A tube comprising a first main electrode,

a second main electrode spaced from said first main electrode, a control electrode an the side of said second main electrode opposite said first main electrode, said second main electrode and said control electrode being spaced close together, whereby no discharge takes place between them and a direct connection between said first main electrode and said control electrode.

12. A tube comprising a first electrode, a second electrode which is perforated and which is spaced from said first electrode, a third electrode on the side of said second electrode opposite said first electrode, said second electrode and said third electrode being spaced close together, whereby no discharge takes place between them and a direct connection between said first electrode and said third electrode.

13. A method of operating a flashing luminous gas discharge tube which consists in starting the tube and intermittently short-circuiting the positive column of the discharge while maintaining current flow through the dark spaces adjacent to at least one of the main electrodes of the tube.

ALFRED J. POTE. 

